Synthesis of crystalline silicate ZSM-12

ABSTRACT

This invention relates to a new and improved form of crystalline silicate identified as zeolite ZSM-12, to a new and useful improvement in synthesizing said crystalline silicate and to use of said crystalline silicate prepared in accordance herewith as a catalyst for organic compound, e.g. hydrocarbon compound, conversion. In the disclosed method for preparing zeolite ZSM-12, a benzyltriethylammonium compound is added to the synthesis reaction mixture.

BACKGROUND OF THE INVENTION

1. Field Of The Invention

This invention relates to a new and improved form of crystalline silicate ZSM-12, to a new and useful improvement in synthesizing said crystalline silicate and to use of the crystalline silicate prepared in accordance herewith as a catalyst for organic compound, e.g. hydrocarbon compound, conversion.

More particularly, this invention relates to an improved method of preparing crystalline silicate ZSM-12 whereby synthesis is facilitated and reproducible and the silicate product exhibits high purity and catalytic utility.

2. Discussion Of Prior Art

Crystalline silicate ZSM-12 and its conventional preparation are taught by U.S. Pat. No. 3,832,449, the entire disclosure of which is incorporated herein by reference. It has a distinctive X-ray diffraction pattern which identifies it from other known crystalline silicates.

U.S. Pat. No. 4,391,785 teaches a method for synthesis of zeolite ZSM-12 from a reaction mixture comprising, as a directing agent, a compound selected from the group consisting of dimethyl pyridinium halide and dimethyl pyrrolidinium halide. U.S. Pat. No. 4,296,083 claims synthesizing zeolites characterized by a constraint index of 1 to 12 and an alumina/silica mole ratio of not greater than 0.083 from a specified reaction mixture containing an organic nitrogen-containing cation provided by an amine identified as being selected from the group consisting of triethylamine, trimethylamine, tripropylamine, ethylenediamine, propanediamine, butanediamine, pentanediamine, hexanediamine, methylamine, ethylamine, propylamine, butylamine, dimethylamine, diethylamine, dipropylamine, benzylamine, aniline, pyridine, piperidine and pyrrolidine.

U.S. Patent 4,151,189 claims a method for synthesizing zeolites ZSM-5, ZSM-12, ZSM-35 and ZSM-38 containing an organic nitrogen cation from a specified reaction mixture containing a primary amine having 2 to 9 carbon atoms as a directing agent. U.S. Pat. No. 4,112,056 teaches a synthesis method for ZSM-12 from a reaction mixture containing tetraethylammonium ions as directions agent. U.S. Pat. No. 4,452,769 (Ser. No. 235,116, filed Feb. 17, 1981) claims a method for synthesizing ZSM-12 from a reaction mixture containing methyltriethylammonium ions as the directing agent.

Applicant knows of no prior art methods for preparing crystalline silicate ZSM-12 utilizing the present improved method.

SUMMARY OF THE INVENTION

An improved reproducible method for preparing an improved crystalline silicate identified as zeolite ZSM-12 over an unusually wide range of aluminum content exhibiting high purity, high crystallinity, catalytic activity and other valuable properties is provided. The method comprises forming a reaction mixture containing sources of alkali metal oxide, an organic nitrogen-containing cation, an oxide of silicon, water and, optionally an oxide of aluminum and having a composition, in terms of mole ratios, within the following ranges:

    ______________________________________                                                       Broad      Preferred                                             ______________________________________                                         SiO.sub.2 /Al.sub.2 O.sub.3                                                                    80-∞   >120-∞                                      H.sub.2 O/OH.sup.-                                                                             40-400       80-300                                            OH.sup.- /SiO.sub.2                                                                            0.02-0.3     0.03-0.2                                          R/(R + M)       0.2-0.8      0.3-0.7                                           ______________________________________                                    

wherein R is a cation derived from a benzyltriethylammonium compound and M is an alkali metal ion, and maintaining the mixture until crystals of the crystalline silicate ZSM-12 are formed. The quantity of OH⁻ is calculated only from the inorganic sources of alkali without any organic base contribution. It is noted that the SiO₂ /Al₂ O₃ molar ratio for the reaction mixture of the present invention can vary over a notably wide range, with an essentially unlimited upper end. It can be infinity or as reasonably close thereto as possible.

Thereafter, the crystals are separated from the liquid and recovered. Reaction conditions required consist of heating the foregoing reaction mixture to a temperature of from about 90° C. to about 175° C. for a period of time of from about 72 hours to about 100 days. A more preferred temperature range is from about 100° C. to about 150° C. with the amount of time at a temperature in such range being from about 48 hours to about 75 days.

The digestion of the gel particles is carried out until crystals form. The solid product is separated from the reaction medium, as by cooling the whole to room temperature, filtering and water washing. The crystalline product of this invention synthesized at higher temperature, e.g. from about 150° C. to about 175° C., exhibits changes in X-ray diffraction peak positions, indicating cell parameter differences from ZSM-12 synthesized by prior methods.

EMBODIMENTS

Zeolite ZSM-12 synthesized under conventional procedure is proven to have catalytic application. When the crystalline silicate is synthesized in accordance with the present method, it exhibits high purity and high crystallinity with no contamination from other silicates, e.g. ZSM-5, and significantly enhanced catalytic activity for certain conversions of interest, including cracking and hydrocracking. The ZSM-12 synthesized hereby has a wider silica/alumina molar ratio range than conventionally prepared ZSM-12, allowing for tailoring that ratio to suit specific purposes. The present method proves to be reproducible and easy to carry out. The ZSM-12, further, exhibits evidence of comprising different cell parameters from conventionally synthesized ZSM-12 when synthesized from the foregoing reaction mixture at a crystallization temperature of from about 150° C. to about 175° C.

The particular effectiveness of the presently required different organic directing agent, i.e. the benzyltriethylammonium compound, when compared with other directing agents, such as those identified above, is believed due to its ability to function as a template in the nucleation and growth of zeolite ZSM-12 crystals. This different organic directing agent functions in this fashion over an unusually wide range of reaction mixture aluminum content, and provides a crystalline ZSM-12 product free from contamination with other silicates, such as ZSM-5.

The organic directing agent required of the present method is a benzyltriethylammonium compound or mixtures thereof. The compound may be, as non-limiting examples, the hydroxide or the halide, e.g. chloride, bromide or iodide.

The reaction mixture composition for the synthesis of synthetic crystalline silicate hereby can be prepared utilizing materials which can supply the appropriate oxide. Such compositions include aluminates, alumina, silicates, silica hydrosol, silica gel, silicic acid and hydroxides. It will be understood that each oxide component utilized in the reaction mixture for preparing zeolite ZSM-12 can be supplied by one or more essential reactants and they can be mixed together in any order. For example, any oxide can be supplied by an aqueous solution, sodium hydroxide or by an aqueous solution of a suitable silicate; the organic cation can be supplied by the directing agent compound of that cation, such as, for example, the hydroxide or a salt, e.g. halide, such as chloride or bromide. The reaction mixture can be prepared either batchwise or continuously. Crystal size and crystallization time for the zeolite ZSM-12 composition will vary with the exact nature of the reaction mixture employed. In general, the crystal morphology of the ZSM-12 synthesized hereby is 1 to 2 micron layered spheres.

The zeolite ZSM-12 composition as prepared hereby can be identified, in terms of mole ratios of oxides and in the anhydrous state, as follows:

(0.9 to 2.5)R₂ O:(0.3 to 2.2)M_(2/n) O:(0.02 to 0.8)Al₂ O₃ :(100)SiO₂

wherein M is at least one cation having a valence n and R is the cation derived from the benzyltriethylammonium compound.

The original cations, e.g. alkali metal, can be replaced, at least in part, by calcination and/or ion exchange with another cation. Thus, the original cations are exchanged into a hydrogen or hydrogen ion precursor form or a form in which the original cation has been replaced by a metal of Groups IIA, IIIA, IVA, IB, IIB, IIIB, IVB, VIB or VIII of the Periodic Table. Thus, for example, it is contemplated to exchange the original cations with ammonium ions or with hydronium ions. Catalytically active forms of these would include, in particular, hydrogen, rare earth metals, aluminum, metals of Groups II and VIII of the Periodic Table and manganese.

The X-ray diffraction pattern of the crystalline silicate product of the present invention has the characteristic lines shown in Table 1.

                  TABLE 1                                                          ______________________________________                                         Interplanar d-Spacing                                                          (A)             Relative Intensity (I/I.sub.o)                                 ______________________________________                                         11.9 ± 0.2   m                                                              10.1 ± 0.2   m                                                              4.76 ± 0.1   w                                                              4.29 ± 0.08  vs                                                             3.98 ± 0.08  m                                                              3.87 ± 0.07  vs                                                             3.49 ± 0.07  w                                                              3.38 ± 0.07  m                                                              3.20 ± 0.06  w                                                              3.05 ± 0.05  w                                                              2.54 ± 0.03  w                                                              ______________________________________                                    

These values were determined by standard technique. The radiation was the K-alpha doublet of copper, and a diffraction equipped with a scintillation counter and a strip chart pen recorder was used. The peak heights, I, and the positions as a function of two times theta, where theta is the Bragg angle, were read from the spectrometer chart. From these, the relative intensities, 100 I/I_(o) where I_(o) is the intensity of the strongest line or peak, and d (obs.), the interplanar spacing in Angstrom units (A) corresponding to the recorded lines, were calculated. In Table 1 the relative intensities are given in terms of the symbols w=weak, m=medium, vs=very strong, etc. Ion exchange of the sodium ions with cations reveals substantially the same pattern with some minor shifts in interplanar spacing and variation in relative intensity. Other minor variations can occur depending on the silicon to aluminum ratio of the particular sample, as well as if it has been subjected to thermal treatment.

When the present crystallization is carried out at a temperature high in the allowable range, e.g. about 150° C. to about 175° C., the X-ray diffraction peak positions formed for the crystalline product of this invention are different from those found for ZSM-12 synthesized by prior methods. This indicates cell parameter differences in the ZSM-12 synthesized under the higher temperature conditions by way of this method.

While the improved crystalline silicate of the present invention may be used in a wide variety of organic compound, e.g. hydrocarbon compound, conversion reactions, it is notably useful in the processes of catalytic cracking and, when combined with a hydrogenation component, hydrocracking. Other conversion processes for which improved zeolite ZSM-12 may be utilized in one or more of its active forms include, for example, olefin or aromatic isomerization.

Synthetic zeolite ZSM-12 prepared in accordance herewith can be used either in the organic nitrogen-containing and alkali metal contaning form, the alkali metal form and hydrogen form or another univalent or multivalent cationic form. It can also be used in intimate combination with a hydrogenating component such as tungsten, vanadium, molybdenum, rhenium, nickel, cobalt, chromium, manganese, or a noble metal such as platinum or palladium where a hydrogenation-dehydrogenation function is to be performed. Such components can be exchanged into the composition, impregnated therein or physically intimately admixed therewith. Such components can be impregnated in or on to zeolite ZSM-12 such as, for example, by, in the case of platinum, treating the zeolite with a platinum metal-containing ion. Suitable platinum compounds for this purpose include chloroplatinic acid, platinous chloride and various compounds containing the platinum amine complex. Combinations of metals and methods for their introduction can also be used.

Synthetic zeolite ZSM-12, when employed either as an adsorbent or as a catalyst in a hydrocarbon conversion process, should be dehydrated at least partially. This can be done by heating to a temperature in the range of from about 200° C. to about 600° C. in an inert atmosphere, such as air, nitrogen, etc. and at atmospheric or subatmospheric pressures for between 1 and 48 hours. Dehydration can also be performed at lower temperature merely by placing the zeolite in a vacuum, but a longer time is required to obtain a particular degree of dehydration. The thermal decomposition product of the newly synthesized ZSM-12 can be prepared by heating same at a temperature up to about 600° C. for from 1 hour to about 48 hours.

As above mentioned, synthetic zeolite ZSM-12 prepared in accordance herewith can have the original cations associated therewith replaced by a wide variety of other cations according to techniques well known in the art. Typical replacing cations include hydrogen, ammonium and metal cations including mixtures thereof. Of the replacing metallic cations, particular preference is given to cations of metals such as rare earths, Mn, Ca, Mg, Zn, Cd, Pd, Ni, Cu, Ti, Al, Sn, Fe and Co.

Typical ion exchange technique would be to contact the synthetic zeolite with a salt of the desired replacing cation or cations. Although a wide variety of salts can be employed, particular preference is given to chlorides, nitrates and sulfates.

Representative ion exchange techniques are disclosed in a wide variety of patents including U.S. Pat. Nos. 3,140,249; 3,140,251; and 3,140,253.

Following contact with the salt solution of the desired replacing cation, the zeolite is then preferably washed with water and dried at a temperature ranging from 65° C. to about 315° C. and thereafter may be calcined in air or other inert gas at temperatures ranging from about 200° C. to about 600° C. for periods of time ranging from 1 to 48 hours or more to produce a catalytically-active thermal decomposition product thereof.

Regardless of the cation replacing the alkali metal in the synthesized form of the zeolite ZSM-12, the spatial arrangement of the aluminum, silicon and oxygen atoms which form the basic crystal lattices of zeolite ZSM-12 remains essentially unchanged by the described replacement of alkali metal as determined by taking an X-ray powder diffraction pattern of the ion-exchanged material.

The crystalline silicate prepared by the instant invention is formed in a wide variety of particle sizes. Generally speaking, the particles can be in the form of a powder, a granule, or a molded product, such as extrudate having particle size sufficient to pass through a 2 mesh (Tyler) screen and be retained on a 400 mesh (Tyler) screen. In cases where the catalyst is molded, such as by extrusion, the crystalline silicate can be extruded before drying or dried or partially dried and then extruded.

In the case of many catalysts, it is desired to incorporate the zeolite ZSM-12 hereby prepared with another material resistant to the temperatures and other conditions employed in certain organic conversion processes. Such matrix materials include active and inactive materials and synthetic or naturally occurring zeolites as well as inorganic materials such as clays, silica and/or metal oxides, e.g. alumina. The latter may be either naturally occurring or in the form of gelatinous precipitates, sols or gels including mixtures of silica and metal oxides. Use of a material in conjuction with the zeolite ZSM-12, i.e. combined therewith, which is active, may enhance the conversion and/or selectivity of the catalyst in certain organic conversion processes. Inactive materials suitably serve as diluents to control the amount of conversion in a given process so that products can be obtained economically and orderly without employing other means for controlling the rate or reaction. Frequently, crystalline silicate materials have been incorporated into naturally occurring clays, e.g. bentonite and kaolin. These materials, i.e. clays, oxides, etc., function, in part, as binders for the catalyst. It is desirable to provide a catalyst having good crush strength, because in a petroleum refinery the catalyst is often subjected to rough handling, which tends to break the catalyst down into powder-like materials which cause problems in processing.

Naturally occurring clays which can be composited with the hereby synthesized zeolite ZSM-12 include the montmorillonite and kaolin families which include the subbentonites, and the kaolins commonly known as Dixie, McNamee, Georgia and Florida clays, or others in which the main mineral constituent is halloysite, kaolinite, dickite, nacrite or anauxite. Such clays can be used in the raw state as originally mined or initially subjected to calcination, acid treatment or chemical modification.

In addition to the foregoing materials, the zeolite ZSM-12 catalyst hereby synthesized can be composited with a porous matrix material such as silica-alumina, silica-magnesia, silica-zirconia, silica-thoria, silica-beryllia, silica-titania, as well as ternary compositions such as silica-alumina-thoria, silica-alumina-zirconia, silica-alumina-magnesia and silica-magnesia-zirconia. The matrix can be in the form of a cogel. A mixture of these components could also be used. The relative proportions of finely divided crystalline silicate and inorganic oxide gel matrix vary widely with the crystalline silicate content ranging from about 1 to about 90 percent by weight, and more usually in the range of about 2 to about 50 percent by weight of the composite.

Employing a catalytically active form of the composition of this invention containing a hydrogenation component, reforming stocks can be reformed employing a temperature between 370° C. and 540° C. The pressure can be between 100 and 1000 psig, but is preferably between 200 and 700 psig. The liquid hourly space velocity is generally between 0.1 and 10 hr⁻¹, preferably between 0.5 and 4 hr⁻¹ and the hydrogen to hydrocarbon mole ratio is generally between 1 and 20, preferably between 4 and 12.

The catalyst can also be used for hydroisomerization of normal paraffins, when provided with a hydrogenation component, e.g. platinum. Hydroisomerization is carried out at a temperature between 90° C. to 370° C., preferably 140° C. to 290° C., with a liquid hourly space velocity between 0.01 and 2 hr⁻¹, preferably between 0.25 and 0.50 hr⁻¹, employing hydrogen such that the hydrogen to hydrocarbon mole ratio is between 1 and 5. Additionally, the catalyst can be used for olefin or aromatics isomerization employing temperatures between 0° C. and 370° C.

The catalyst can also be used for reducing the pour point of gas oils. This process is carried out at a liquid hourly space velocity between about 10 and about 30 hr⁻¹ and a temperature between about 400° C. and about 540° C.

Other reactions which can be accomplished employing the catalyst of this invention containing a metal, e.g. platinum, include hydrogenation-dehydrogenation reactions and desulfurization reactions, olefin polymerization (oligomerization), and other organic compound conversions such as the conversion of alcohols (e.g. methanol) to hydrocarbons.

In order to more fully illustrate the nature of the invention and the manner of practicing same, the following examples are presented. In the examples, whenever adsorption data are set forth for comparison of sorptive capacities for water, cyclohexane and n-hexane, they were determined as follows:

A weighed sample of the calcined adsorbant contacted with the desired pure adsorbate vapor in an adsorption chamber, evacuated to 1 mm and contacted with 12 mm Hg of water vapor or 20 mm Hg of n-hexane, or cyclohexane vapor, pressures less than the vapor-liquid equilibrium pressure of the respective adsorbate at room temperature. The pressure was kept constant (within about ±0.5 mm) by additon of adsorbate vapor controlled by a manostat during the adsorption period, which did not exceed about 8 hours. As adsorbate was adsorbed by the sorbant material, the decrease in pressure caused the monostat to open a valve which admitted more adsorbate vapor to the chamber to restore the above control pressures. Sorption was complete when the pressure change was not sufficient to activate the monostat. The increase in weight was calculated as the adsorption capacity of the sample in g/100 g of calcined adsorbant.

When Alpha Value is examined, it is noted that the Alpha Value is an approximate indication of the catalytic cracking activity of the catalyst compared to a standard catalyst and it gives the relative rate constant (rate of normal hexane conversion per volume of catalyst per unit time). It is based on the activity of the highly active silica-alumina cracking catalyst taken as an Alpha of 1 (Rate Constant=0.016 sec⁻¹). In the case of zeolite HZSM-5, only 174 ppm of tetrahedrally coordinated Al₂ O₃ are required to provide an Alpha Value of 1. The Alpha Test is described in U.S. Pat. No. 3,354,078 and in The Journal of Catalysis, Vol. IV, pp. 522-529 (August 1965), each incorporated herein by reference as to that description. The zeolite tested in this Alpha Test must be in the hydrogen or hydronium form. This may be accomplished by hydrolysis of the zeolite followed by calcination, by contact of the zeolite with an ammonium salt or acid solution followed by calcination, or by calcination of the zeolite if it contains a hydrogen precursor by way of its synthesis.

EXAMPLE 1

Two separate solutions were prepared to be composed of:

(A) 3.5 grams NaOH and 15.0 grams H₂ O, and

(B) 19.5 grams benzyltriethylammonium chloride (97%) and 25.0 grams H₂ O.

Solutions A and B were then mixed together, and the mixture was added to 188.0 grams colloidal silica (30% solution). The total was then thoroughly mixed. The mixture, which had the composition in mole ratios:

    ______________________________________                                         SiO.sub.2 /Al.sub.2 O.sub.3                                                                          = ∞                                                H.sub.2 O/OH.sup.-    = 109                                                    OH.sup.- /SiO.sub.2   = 0.093                                                  R/(R + Na)            = 0.49                                                   ______________________________________                                    

wherein R is the cation derived from benzyltriethylammonium chloride, was then allowed to crystallize in a polypropylene jar under static conditions at 100° C. for 47 days. The product crystals were separated from the remaining mixture, filtered, washed with water and dried at 118° C.

The crystalline product was submitted for chemical analysis and X-ray diffraction analysis. Chemical analysis proved the composition of the product crystals to be as follows:

    ______________________________________                                         7.9 wt. %        C                                                             0.76 wt. %       N                                                             0.68 wt. %       Na                                                            585 ppm          Al.sub.2 O.sub.3                                              86.6 wt. %       SiO.sub.2                                                     88.8 wt. %       Ash                                                           2509             SiO.sub.2 /Al.sub.2 O.sub.3 molar ratio                       ______________________________________                                    

Table 2 lists the X-ray diffraction pattern of the crystalline product of this example. The crystals were dried at 118° C. in air prior to X-ray analysis.

                  TABLE 2                                                          ______________________________________                                          Interplanar   Observed Relative                                               d-Spacings (A) 2θ Intensities, I/I.sub.o                                 ______________________________________                                         11.93          7.41     17                                                     11.60          7.62     12                                                     10.13          8.73     7                                                      6.02           14.70    1                                                      5.82           15.23    1                                                      4.69           18.90    8                                                      4.45           19.95    2                                                      4.26           20.855   100                                                    4.08           21.79    5                                                      3.98           22.35    11                                                     3.865          23.00    58                                                     3.75           23.74    4                                                      3.64           24.46    3                                                      3.47           25.66    18                                                     3.37           26.42    19                                                     3.19           27.955   7                                                      3.14           28.455   2                                                      3.05           29.23    3                                                      2.93           30.51    2                                                      2.88           31.00    3                                                      2.65           33.82    4                                                      2.585          34.69    2                                                      2.525          35.55    19                                                     2.47           36.36    3                                                      2.44           36.83    3                                                      2.35           38.34    3                                                      2.32           38.75    3                                                      2.13           42.38    2                                                      2.08           43.59    2                                                      2.04           44.43    8                                                      1.99           45.50    3                                                      1.95           46.58    4                                                      1.90           47.83    2                                                      1.84           49.54    2                                                      ______________________________________                                    

These X-ray results indicate a 110% crystalline ZSM-12 structure.

A quantity of the product of this example was calcined at 540° C. for 16 hours in air, and then tested for sorption properties. The results indicated:

3.3 wt. % cyclohexane sorbed,

2.3 wt. % n-hexane sorbed, and

5.0 wt. % water sorbed.

EXAMPLE 2

Two separate solutions were prepared to be composed of:

(A) 3.5 grams NaOH and 30.0 grams H₂ O, and

(B) 39.0 grams benzyltriethylammonium chloride (97%) and 50 grams H₂ O.

Solutions A and B were then mixed together, and the mixture was added to 376 grams colloidal silica (30%). The total was then thoroughly mixed. The mixture, which had the composition in mole ratios:

    ______________________________________                                                SiO.sub.2 /Al.sub.2 O.sub.3                                                                   = ∞                                                       H.sub.2 O/OH.sup.-                                                                            = 218                                                           OH.sup.- /SiO.sub.2                                                                           = 0.047                                                         R/(R + Na)     = 0.65                                                   ______________________________________                                    

was then allowed to crystallize in a polypropylene jar under static conditions at 100° C. for 73 days. The product crystals were separated from the remaining mixture, filtered, washed with water and dried at 118° C.

The crystalline product was submitted for chemical analysis and X-ray diffraction analysis. Chemical analysis proved the composition of the product crystals to be as follows:

    ______________________________________                                         8.0 wt. %        C                                                             0.80 wt. %       N                                                             0.38 wt. %       Na                                                            440 ppm          Al.sub.2 O.sub.3                                              87.5 wt. %       SiO.sub.2                                                     88.22 wt. %      Ash                                                           3364             SiO.sub.2 /Al.sub.2 O.sub.3 molar ratio                       ______________________________________                                    

Table 3 lists the X-ray diffraction pattern of the crystalline product of this example. The crystals were dried at 118° C. in air prior to X-ray analysis.

                  TABLE 3                                                          ______________________________________                                         Interplanar    Observed Relative                                               d-Spacings (A) 2θ Intensities, I/I.sub.o                                 ______________________________________                                         11.86           7.455   16                                                     11.54           7.66    14                                                     10.09           8.76    7                                                      6.02           14.72    1                                                      5.81           15.24    1                                                      4.72           18.82    8                                                      4.65           19.08    9                                                      4.44           20.01    3                                                      4.25            20.895  100                                                    4.07           21.83    6                                                      3.98           22.36    11                                                     3.84           23.14    62                                                     3.75           23.74    5                                                      3.63            24.505  4                                                      3.46           25.73    19                                                     3.36           26.56    19                                                     3.18           28.01    8                                                      3.14           28.46    4                                                      3.05           29.26    4                                                      2.93           30.55    3                                                      2.88           31.04    3                                                      2.64            33.955  4                                                      2.58           34.77    2                                                      2.52           35.56    21                                                     2.47           36.41    2                                                      2.44            36.885  3                                                      2.35           38.35    3                                                      2.32           38.74    2                                                      2.13            42.415  2                                                      2.11           42.81    2                                                      2.07           43.63    2                                                      2.04           44.42    10                                                     1.99           45.56    3                                                      1.95           46.59    4                                                      1.90           47.83    2                                                      1.84           49.52    2                                                      ______________________________________                                    

These X-ray results indicate a 100% crystalline ZSM-12 structure.

A quantity of the product of this example was calcined at 540° C. for 16 hours in air, and then tested for sorption properties. The results indicated:

7.8 wt. % cyclohexane sorbed,

1.4 wt. % n-hexane sorbed, and

3.3 wt. % water sorbed.

EXAMPLE 3

Two separate solutions were prepared to be composed of:

(A) 3.5 grams NaOH and 15.0 grams H₂ O, and

(B) 19.5 grams benzyltriethylammonium chloride (97%) and 25.0 grams H₂ O.

Solutions A and B were then mixed together, and the mixture was added to 188 grams colloidal silica (30%). The total was then thoroughly mixed. The mixture, which had the composition in mole ratios:

    ______________________________________                                         SiO.sub.2 /Al.sub.2 O.sub.3                                                                          = ∞                                                H.sub.2 O/OH.sup.-    = 109                                                    OH.sup.- /SiO.sub.2   = 0.093                                                  R/(R + Na)            = 0.48                                                   ______________________________________                                    

was then allowed to crystallize in a polypropylene jar under static conditions at 100° C. for 48 days. The product crystals were separated from the remaining mixture, filtered, washed with water and dried at 118° C.

The crystalline product was submitted for chemical analysis and X-ray diffraction analysis. Chemical analysis showed the following product components:

    ______________________________________                                         0.69 wt. %       N                                                             0.51 wt. %       Na                                                            650 ppm          Al.sub.2 O.sub.3                                              87.42 wt. %      SiO.sub.2                                                     88.37 wt. %      Ash                                                           2286             SiO.sub.2 /Al.sub.2 O.sub.3 molar ratio                       ______________________________________                                    

X-ray results indicated a 105% crystalline ZSM-12 structure.

A quantity of the product of this example was calcined at 540° C. for 16 hours in air, and then tested for sorption properties. The results indicated:

8.4 wt. % cyclohexane sorbed,

6.4 wt. % n-hexane sorbed, and

3.3 wt. % water sorbed.

EXAMPLE 4

Two separate solutions were prepared to be composed of:

(A) 6.0 grams NaOH and 15.0 grams H₂ O, and

(B) 19.5 grams benzyltriethylammonium chloride (97%) and 25.0 grams H₂ O.

Solutions A and B were then mixed together, and the mixture was added to 188 grams colloidal silica (30%). The total was then thoroughly mixed. The mixture, which had the composition in mole ratios:

    ______________________________________                                                SiO.sub.2 /Al.sub.2 O.sub.3                                                                   = ∞                                                       H.sub.2 O/OH.sup.-                                                                            = 63.7                                                          OH.sup.- /SiO.sub.2                                                                           = 0.16                                                          R/(R + Na)     = 0.36                                                   ______________________________________                                                 was then allowed to crystallize in a polypropylene jar under static      conditions at 100° C. for 69 days. The product crystals were      separated from the remaining mixture, filtered, washed with water and      dried at 118° C.

The crystalline product was submitted for chemical analysis and X-ray diffraction analysis. Chemical analysis showed the composition of the product crystals to include 0.41 wt. % nitrogen. X-ray results indicated crystalline ZSM-12 and some non-ZSM-12 material.

EXAMPLE 5

Two separate solutions were prepared to be composed of:

(A) 3.7 grams LiOH.H₂ O and 15.0 grams H₂ O, and

(B) 19.5 grams benzyltriethylammonium chloride (97%) and 25.0 grams H₂ O.

Solutions A and B were then mixed together, and the mixture was added to 188 grams colloidal silica (30%). The total was then thoroughly mixed. The mixture, which had the composition in mole ratios:

    ______________________________________                                         SiO.sub.2 /Al.sub.2 O.sub.3                                                                          = ∞                                                H.sub.2 O/OH.sup.-    = 109                                                    OH.sup.- /SiO.sub.2   = 0.094                                                  R/(R + Li)            = 0.48                                                   ______________________________________                                    

was then allowed to crystallize in a polypropylene jar under static conditions at 100° C. for 27 days. The product crystals were separated from the remaining mixture, filtered, washed with water and dried at 118° C.

The crystalline product was submitted for chemical analysis and X-ray diffraction analysis. Chemical analysis proved the composition of the product crystals to be as follows:

    ______________________________________                                         7.0 wt. %        C                                                             0.60 wt. %       N                                                             0.34 wt. %       Li                                                            0.18 wt. %       Na                                                            0.15 wt. %       Al.sub.2 O.sub.3                                              83.61 wt. %      SiO.sub.2                                                     86.68 wt. %      Ash                                                           947              SiO.sub.2 /Al.sub.2 O.sub.3 molar ratio                       ______________________________________                                    

X-ray results indicated a 95% crystalline ZSM-12 structure.

A quantity of the product of this example was calcined at 540° C. for 16 hours in air, and then tested for sorption properties. The results indicated:

5.7 wt. % cyclohexane sorbed,

5.0 wt. % n-hexane sorbed, and

3.7 wt. % water sorbed.

EXAMPLE 6

Two separate solutions were prepared to be composed of:

(A) 6.12 grams NaOH and 70.0 grams H₂ O, and

(B) 68.2 grams benzyltriethylammonium chloride (98%) and 120 grams H₂ O.

Solutions A and B were then mixed together, and the mixture was added to 658 grams colloidal silica (30%). The total was then thoroughly mixed. The mixture, which had the composition in mole ratios:

    ______________________________________                                          SiO.sub.2 /Al.sub.2 O.sub.3                                                                         = ∞                                                H.sub.2 O/OH.sup.-    = 241                                                    OH.sup.- /SiO.sub.2   = 0.046                                                  R/(R + Na)            = 0.66                                                   ______________________________________                                    

was then allowed to crystallize in a teflon jar under static conditions at 150° C. for 7 days. The product crystals were separated from the remaining mixture, filtered, washed with water and dried at 118° C.

The crystalline product was submitted for chemical analysis and X-ray diffraction analysis. Chemical analysis proved the composition of the product crystals include the following:

    ______________________________________                                         7.30 wt. %       C                                                             0.67 wt. %       N                                                             0.86 wt. %       Na                                                            630 ppm          Al.sub.2 O.sub.3                                              88.29 wt. %      SiO.sub.2                                                     90.62 wt. %      Ash                                                           2381             SiO.sub.2 /Al.sub.2 O.sub.3 molar ratio                       ______________________________________                                    

Table 4 lists the X-ray diffraction pattern of the crystalline product of this example. The crystals were calcined at 540° C. in air prior to X-ray analysis.

                  TABLE 4                                                          ______________________________________                                         Interplanar    Observed Relative                                               d-Spacings (A) 2θ Intensities, I/I.sub.o                                 ______________________________________                                         11.68           7.57    50                                                     11.41           7.75    34                                                     9.87            8.96    24                                                     7.19           12.31    3                                                      5.93           14.94    5                                                      5.75           15.41    6                                                      4.70           18.88    10                                                     4.61           19.26    8                                                      4.40           20.17    5                                                      4.21           21.08    100                                                    4.13           21.49    5                                                      4.03           22.05    5                                                      3.93           22.60    11                                                     3.85           23.13    31                                                     3.80           23.42    23                                                     3.71           23.97    3                                                      3.61           24.65    3                                                      3.51           25.35    8                                                      3.44           25.92    18                                                     3.36           26.50    12                                                     3.30           27.01    12                                                     3.17           28.17    7                                                      3.11           28.70    2                                                      3.03           29.48    5                                                      2.87           31.15    8                                                      2.64           33.97    4                                                      2.58           34.84    3                                                      2.50           35.89    18                                                     2.45           36.72    4                                                      2.42           37.15    5                                                      2.38           37.87    1                                                      2.32           38.72    4                                                      ______________________________________                                    

These X-ray results indicate an 85% crystalline ZSM-12 structure with changes in peak positions indicating cell parameter differences from reference ZSM-12 material.

A quantity of the product of this example was calcined at 540° C. for 16 hours in air, and then tested for sorption properties. The results indicated:

5.0 wt. % n-hexane sorbed, and

2.2 wt. % water sorbed.

EXAMPLE 7

Twenty-five grams of the dried zeolite ZSM-12 product from Example 6 were calcined in air at 540° C. for 10 hours. Five ammonium ion exchanges were carried out at 85° C. with 20 cc of 5% NH₄ Cl solution per gram of ZSM-12 for 1 hour each to reduce the Na level of the ZSM-12 to less than 0.01%. The ion exchanged material was washed, dried and sized to 14/25 mesh prior to a final air activation step of 10 hours at 540° C. The product sample was tested in the Alpha Test and found to have an Alpha Value of 3. 

What is claimed is:
 1. A method for synthesizing a crystalline silicate having a composition in the anhydrous state, expressed in terms of mole ratios of oxides, as follows:(0.9 to 2.5)R₂ O:(0.3 to 2.2)M_(2/n) O:(0.02 to 0.8)Al₂ O₃ :(100)SiO₂ wherein M is at least one alkali metal cation having the valence n, and R is benzyltriethylammonium cation, and exhibiting a characteristic X-ray diffraction pattern as shown in Table 1 of the specification, which comprises preparing a mixture containing sources of alkali metal oxide, an organic nitrogen-containing cation, an oxide of silicon and water and having a composition, in terms of mole ratios, within the following ranges:

    ______________________________________                                         SiO.sub.2 /Al.sub.2 O.sub.3                                                                         = 80-∞                                              H.sub.2 O/OH.sup.-   = 40-400                                                  OH.sup.- /SiO.sub.2  = 0.02-0.3                                                R/(R + M)            = 0.2-0.8                                                 ______________________________________                                    

wherein M and R are as above defined, and maintaining the mixture at a temperature of from about 90° C. to about 175° C. until crystals of the crystalline silicate are formed.
 2. The method of claim 1 wherein said mixture has a composition, in terms of mole ratios, as follows:

    ______________________________________                                         SiO.sub.2 /Al.sub.2 O.sub.3                                                                         = >120-∞                                            H.sub.2 O/OH.sup.-   = 80-300                                                  OH.sup.- /SiO.sub.2  = 0.03-0.2                                                R/(R + M)            = 0.3-0.7                                                 ______________________________________                                    


3. The method of claim 1 wherein said benzyltriethylammonium cation is derived from a salt selected from the group consisting of the halide and hydroxide.
 4. The method of claim 3 wherein said salt is the halide
 5. The method of claim 4 wherein said halide is chloride.
 6. A synthetic crystalline silicate having a composition in the anhydrous state, expressed in terms of mole ratios of oxides, as follows:(0.9 to 2.5)R₂ O:(0.3 to 2.2)M_(2/n) O:(0.02 to 0.8)Al₂ O₃ :(100)SiO₂ wherein M is at least one alkali metal cation having the valence n, and R is benzyltriethylammonium cation, and exhibiting a characteristic X-ray diffraction pattern as shown in Table 1 of the specification.
 7. The synthetic crystalline silicate of claim 6 wherein said benzyltriethylammonium cation is derived from a salt selected from the group consisting of halide and hydroxide.
 8. The synthetic crystalline silicate of claim 7 wherein said salt is the halide.
 9. The synthetic crystalline silicate of claim 6 wherein M is sodium or lithium.
 10. A synthetic crystalline silicate having a composition in the anhydrous state, expressed in terms of mole ratios of oxides, as follows:(0.9 to 2.5)R₂ O:(0.3 to 2.2)M_(2/n) O:(0.02 to 0.8)Al₂ O₃ :(100)SiO₂ wherein R is benzyltriethylammonium cation; wherein M is (a), (b) or mixtures of (a) and (b) and N is the valence of M wherein (a) is at least one alkali metal cation and where (b) is a cation or a mixture of cations selected from the group consisting of hydrogen and hydrogen precursors, rare earth metals, and metals from Groups IIA, IIIA, IVA, IB, IIB, IIIB, IVB, VIB and VIII of the Periodic Table of Elements, and wherein M is (a) in the as-synthesized synthetic crystalline silicate and wherein M is (b) by ion-exchange of the as-synthesized, synthetic crystalline silicate which synthetic crystalline silicate exhibits a characteristic X-ray diffraction pattern as shown in Table 1 of the specification.
 11. The synthetic crystalline silicate of claim 10 wherein (b) is hydrogen or a hydrogen precursor.
 12. The synthetic crystalline silicate of claim 1 wherein (b) is hydrogen or a hydrogen precursor.
 13. The synthetic crystalline silicate of claim 1 wherein (b) is hydrogen or a hydrogen precursor.
 14. The synthetic crystalline silicate of claim 1 wherein (b) is hydrogen or a hydrogen precursor.
 15. The synthetic crystalline silicate of claim 10 wherein said benzyltriethylammonium cation is derived from a salt selected from the group consisting of halide and hydroxide.
 16. The synthetic crystalline silicate of claim 15 wherein the salt is halide.
 17. The synthetic crystalline silicate of claim 10 wherein M is sodium or lithium. 